1. Field of the Invention
This invention relates to a power converter that makes a current flow in both directions by being connected to a load.
A power converter that makes a current flow in both directions performs charging and discharging by switching a voltage polarity and the like applied and is used, for example, for measuring charging and discharging characteristics and the like or determining quality of the battery when a secondary battery and the like are rendered as loads (for example, see PTL 1).
The power converter measures each voltage and each current when charging the secondary battery to be measured, when opening a circuit after charging, when opening the circuit after discharging for a defined time, when opening the circuit after aging, and the like, measures the charging and discharging characteristics of the secondary battery and determines quality of the secondary battery to be measured by comparing measurement data with each value of a determination table prepared in advance. As described above, power supply when charging the secondary battery to be measured or an operation as an electronic load when discharging is performed by the power converter (bidirectional power supply).
2. Description of the Prior Art
FIG. 7 is an explanatory diagram illustrating a configuration of a power converter of the prior art. In an illustrated power converter 100, a secondary side DC terminal of a bidirectional power supply device 101 is connected to a full-bridge circuit 102 and is connected to a load 103 through the full-bridge circuit 102.
For example, the full-bridge circuit 102 is configured of four semiconductor switches such as IGBTs and is wiring connected so that an output voltage of the bidirectional power supply device 101 is applied across two input points.
Furthermore, two output points of the full-bridge circuit 102 are respectively connected to inductors 104 and 105, and are connected to the load 103 through the inductors 104 and 105. Specifically, one end of the inductor 104 is connected to a high potential side electrode of the load 103 and one end of the inductor 105 is connected to a low potential side electrode of the load 103.
For example, a current sensor (or current detecting shunt resistor) 106 detecting the current flowing to the load 103 is provided between the inductor 104 and the high potential side electrode of the load 103 and is wiring connected, so that a detected current value is output to a control section 113 (here, illustration of the wiring connection is omitted).
An output capacitor 107 is connected between a connection point of the current sensor (current detecting shunt resistor) 106 and the load 103 and a connection point of the inductor 105 and the load 103. Furthermore, between the bidirectional power supply device 101 and the full-bridge circuit 102 an input capacitor 108 is connected between input points of the full-bridge circuit 102, and a resistor 109 is connected in parallel to the input capacitor 108.
The power converter 100 includes an AC/DC conversion power supply section 110 and is wiring connected so that DC power output from the AC/DC conversion power supply section 110 is supplied to a control power supply section 111 and a DC fan 112.
The control section 113 is operated by power output from the control power supply section 111 and has a processor and the like that controls a switch operation of each semiconductor switch configuring the full-bridge circuit 102 for example, according to a control protocol that is preset or in response to a code or a command input from the outside, and the like.
Next, an operation will be described.
AC power is respectively supplied from the outside to the bidirectional power supply device 101 and the AC/DC conversion power supply section 110.
As described above, the AC/DC conversion power supply section 110 into which AC power is input generates a predetermined DC voltage and supplies the DC voltage to the control power supply section 111 and the DC fan 112.
The control power supply section 111 generates a voltage of the power supply supplied to the control section 113 and supplies the voltage of the power supply to the control section 113 by using the DC voltage input from the AC/DC conversion power supply section 110. Furthermore, the DC fan to which the DC voltage is supplied from the AC/DC conversion power supply section 110 is operated and cooling of the inside of the power converter 100 is performed.
The control section 113 actuated by supply of the voltage of the power supply controls the switch connection of each semiconductor switch of the full-bridge circuit 102 and applies the output voltage of the bidirectional power supply device 101 to the load 103. Furthermore, a current discharged from the load 103 flows to the bidirectional power supply device 101 that is operated as an electronic load.
The switch connection as described above is performed, the charging current or the discharging current flowing to the load 103 is detected by the current sensor (current detecting shunt resistor) 106, the detected current value is input into the control section 113, for example, and the measurement of charging or discharging characteristics of the load 103 is performed.